In the first quarter of 2012, Sweden took in almost 20% of all venture capital invested in the European Union. / John Foxx, Getty Images

by Jon Swartz, USA TODAY, @jswartz

by Jon Swartz, USA TODAY, @jswartz

SAN FRANCISCO - If music service Spotify landed Stockholm on the high-tech map, companies such as Klarna underscore its growing influence.

Klarna CEO Sebastian Siemiatkowski swung through town this week to meet investors at Sequoia Capital and spread the word about his online retail payments start-up. Though it has earned a solid reputation in Europe - not to mention $200 million in revenue last year - Klarna ("clear" in Swedish) has yet to make its debut in the USA.

That might change soon, as millions of consumers turn to smartphones and tablets to make purchases. Klarna, an 800-person operation based in Stockholm, is eyeing the U.S. market.

"We're not in the U.S. yet, but there is lots of friction," says Siemiatkowski, who counts Spotify CEO Daniel Ek among his influences. That music-sharing site planted Stockholm as a major tech hub, joined by Klarna, mobile-games maker King.com and iZettle, which sells a device that allows credit card payments on mobile phones. (Niklas Zennstrom, a Swede, co-founded Skype.)

Investment figures bear that out. In the first quarter of 2012, Sweden took in almost 20% of all venture capital invested in the European Union, trailing only Germany, according to data from the European Private Equity and Venture Capital Association.

The honor roll includes open-source database MySQL, which sold to Sun Microsystems, for $1 billion in 2008, and business software firm QlikTech, worth nearly $2 billion. Video game firm DICE is now owned by Electronic Arts, and Spotify boasts 20 million users.

Siemiatkowski and others contend Sweden is benefiting from a wired population and a national affinity for engineering and design. And that Stockholm weather: Many believe the long, dark winters may actually boost productivity as developers and programmers are more likely to stay indoors.